The court case which could decide if Germany's small extreme right-wing National Democratic Party is to be banned has begun in Karlsruhe, with the interior minister Otto Schily defending the use of paid informants within the organisation.

The government decision to apply for a ban followed rising concern over a string of violent attacks blamed on neo-Nazi groups and their skinhead followers.

Schily has been under fire for his handling of the case

But the process got bogged down when details of informers emerged, giving rise to fears that the spies may have acted as agents provocateurs.

The NPD is electorally insignificant - it has no seats in the Bundestag.

But when it was blamed for inciting a series of hate crimes, the government decided to act.

The application to ban the tiny party won the backing of both houses of parliament.

But revelations that at least 30 party officials had acted as paid informers raised questions as to the admissibility of their evidence.

'From the NPD flesh'

The interior minister Otto Schily has now defended their actions before the constitutional court.

He said that the informers for the secret services "were from the flesh of the NPD", as he put it - they had grown up within the organisation.

The NPD claims the spies were agents provocateurs who had steered the party from outside.

The NPD lawyer, Horst Mahler, said at least two senior informers had had a formative influence on the party.

Guenter Beckstein, the Bavarian Interior Minister supporting the ban, called it "an unappetising and aggressive party".

He said an informer was not like a security agency employee who received orders but simply someone who gave information to the state for a few hundred marks a month.

The court is expected to rule on whether the case proceeds next month.